If available, use the hardware output.level to control the volume.

With this change, there's a single outputs.level control: either the
hardware one or software one. Consequently, there can't be control
name clashes and there's no need to move hardware's top-level controls
into the "hw/" group.

sndiod/dev.c

@@ -349,8 +349,26 @@ dev_midi_vol(struct dev *d, struct slot *s)
 void
 dev_midi_master(struct dev *d)
 {
+	struct ctl *c;
+	unsigned int master, v;
 	struct sysex x;
 
+	if (d->master_enabled)
+		master = d->master;
+	else {
+		master = 0;
+		for (c = d->ctl_list; c != NULL; c = c->next) {
+			if (c->type != CTL_NUM ||
+			    strcmp(c->group, "") != 0 ||
+			    strcmp(c->node0.name, "output") != 0 ||
+			    strcmp(c->func, "level") != 0)
+				continue;
+			v = (c->curval * 127 + c->maxval / 2) / c->maxval;
+			if (master < v)
+				master = v;
+		}
+	}
+
 	memset(&x, 0, sizeof(struct sysex));
 	x.start = SYSEX_START;
 	x.type = SYSEX_TYPE_RT;
@@ -358,7 +376,7 @@ dev_midi_master(struct dev *d)
 	x.id0 = SYSEX_CONTROL;
 	x.id1 = SYSEX_MASTER;
 	x.u.master.fine = 0;
-	x.u.master.coarse = d->master;
+	x.u.master.coarse = master;
 	x.u.master.end = SYSEX_END;
 	midi_send(d->midi, (unsigned char *)&x, SYSEX_SIZE(master));
 }
@@ -442,8 +460,10 @@ dev_midi_omsg(void *arg, unsigned char *msg, int len)
 		if (x->id0 == SYSEX_CONTROL && x->id1 == SYSEX_MASTER) {
 			if (len == SYSEX_SIZE(master)) {
 				dev_master(d, x->u.master.coarse);
-				dev_onval(d, CTLADDR_MASTER,
-				    x->u.master.coarse);
+				if (d->master_enabled) {
+					dev_onval(d, CTLADDR_MASTER,
+					   x->u.master.coarse);
+				}
 			}
 			return;
 		}
@@ -655,7 +675,8 @@ dev_mix_adjvol(struct dev *d)
 		}
 		if (weight > i->opt->maxweight)
 			weight = i->opt->maxweight;
-		i->mix.weight = ADATA_MUL(weight, MIDI_TO_ADATA(d->master));
+		i->mix.weight = d->master_enabled ?
+		    ADATA_MUL(weight, MIDI_TO_ADATA(d->master)) : weight;
 #ifdef DEBUG
 		if (log_level >= 3) {
 			slot_log(i);
@@ -946,15 +967,30 @@ dev_onmove(struct dev *d, int delta)
 void
 dev_master(struct dev *d, unsigned int master)
 {
+	struct ctl *c;
+	unsigned int v;
+
 	if (log_level >= 2) {
 		dev_log(d);
 		log_puts(": master volume set to ");
 		log_putu(master);
 		log_puts("\n");
 	}
-	d->master = master;
-	if (d->mode & MODE_PLAY)
-		dev_mix_adjvol(d);
+	if (d->master_enabled) {
+		d->master = master;
+		if (d->mode & MODE_PLAY)
+			dev_mix_adjvol(d);
+	} else {
+		for (c = d->ctl_list; c != NULL; c = c->next) {
+			if (c->type != CTL_NUM ||
+			    strcmp(c->group, "") != 0 ||
+			    strcmp(c->node0.name, "output") != 0 ||
+			    strcmp(c->func, "level") != 0)
+				continue;
+			v = (master * c->maxval + 64) / 127;
+			dev_setctl(d, c->addr, v);
+		}
+	}
 }
 
 /*
@@ -1121,6 +1157,7 @@ dev_open(struct dev *d)
 	int i;
 	char name[CTL_NAMEMAX];
 
+	d->master_enabled = 0;
 	d->mode = d->reqmode;
 	d->round = d->reqround;
 	d->bufsz = d->reqbufsz;
@@ -1149,8 +1186,6 @@ dev_open(struct dev *d)
 		    name, -1, "level",
 		    NULL, -1, 127, d->slot[i].vol);
 	}
-	dev_addctl(d, "", CTL_NUM,
-	    CTLADDR_MASTER, "output", -1, "level", NULL, -1, 127, d->master);
 
 	d->pstate = DEV_INIT;
 	return 1;
@@ -2337,8 +2372,36 @@ dev_rmctl(struct dev *d, int addr)
 void
 dev_ctlsync(struct dev *d)
 {
+	struct ctl *c;
 	struct ctlslot *s;
-	int i;
+	int found, i;
+
+	found = 0;
+	for (c = d->ctl_list; c != NULL; c = c->next) {
+		if (c->addr != CTLADDR_MASTER &&
+		    c->type == CTL_NUM &&
+		    strcmp(c->group, "") == 0 &&
+		    strcmp(c->node0.name, "output") == 0 &&
+		    strcmp(c->func, "level") == 0)
+			found = 1;
+	}
+
+	if (d->master_enabled && found) {
+		if (log_level >= 2) {
+			dev_log(d);
+			log_puts(": software master level control disabled\n");
+		}
+		d->master_enabled = 0;
+		dev_rmctl(d, CTLADDR_MASTER);
+	} else if (!d->master_enabled && !found) {
+		if (log_level >= 2) {
+			dev_log(d);
+			log_puts(": software master level control enabled\n");
+		}
+		d->master_enabled = 1;
+		dev_addctl(d, "", CTL_NUM, CTLADDR_MASTER,
+		    "output", -1, "level", NULL, -1, 127, d->master);
+	}
 
 	for (s = d->ctlslot, i = DEV_NCTLSLOT; i > 0; i--, s++) {
 		if (s->ops)
@@ -2392,8 +2455,10 @@ dev_setctl(struct dev *d, int addr, int val)
 		dev_ref(d);
 	} else {
 		if (addr == CTLADDR_MASTER) {
-			dev_master(d, val);
-			dev_midi_master(d);
+			if (d->master_enabled) {
+				dev_master(d, val);
+				dev_midi_master(d);
+			}
 		} else {
 			num = addr - CTLADDR_SLOT_LEVEL(0);
 			slot_setvol(d->slot + num, val);

sndiod/dev.h

@@ -244,7 +244,9 @@ struct dev {
 #define MMC_START	2			/* attempting to start */
 #define MMC_RUN		3			/* started */
 	unsigned int tstate;			/* one of above */
-	unsigned int master;			/* master volume controller */
+
+	unsigned int master;			/* software vol. knob */
+	unsigned int master_enabled;		/* 1 if h/w has no vo. knob */
 
 	/*
 	 * control

sndiod/dev_sioctl.c

@@ -65,18 +65,17 @@ dev_sioctl_ondesc(void *arg, struct sioctl_desc *desc, int val)
 	dev_rmctl(d, addr);
 
 	/*
-	 * prefix group names we use (top-level and "app") with "hw."
+	 * prefix group names we use (currently "app") with "hw/"
 	 * to ensure that all controls have unique names when multiple
 	 * sndiod's are chained
 	 */
-	if (desc->group[0] == 0)
-		group = GROUP_PREFIX;
-	else {
+	if (strcmp(desc->group, "app") == 0) {
 		group = group_buf;
 		if (snprintf(group_buf, CTL_NAMEMAX, GROUP_PREFIX "/%s",
 		    desc->group) >= CTL_NAMEMAX)
 			return;
-	}
+	} else
+		group = desc->group;
 
 	dev_addctl(d, group, desc->type, addr,
 	    desc->node0.name, desc->node0.unit, desc->func,